by Oren Dorell, USA TODAY

by Oren Dorell, USA TODAY

World powers failed to reach an interim deal with Iran over its disputed nuclear program after lengthy talks in Geneva despite days of encouraging signs from the White House that a deal was imminent.

Catherine Ashton, the European Union's top diplomat, said talks will resume on Nov. 20 in Geneva.

Ashton said there had been, "concrete progress but some differences remain," BBC reports.

The news came as Secretary of State John Kerry was joined by foreign ministers from the United Kingdom, France, Russia, China and Germany to hold a series of meetings with each other and with Iran's delegation, headed by Zarif.

France in particular objected to the proposed deal, questioning whether it would go far enough to limit Tehran's nuclear ambitions, AFP reported. French Foreign Minister Laurent Fabius said Iran's continued operations at its Arak nuclear reactor and its enriched uranium stockpiles should be addressed to remove Iran from the path of developing the capability to build a nuclear weapon without detection by foreign monitors.

"As I speak to you, I cannot say there is any certainty that we can conclude," Fabius said on France Inter radio, adding the country would reject a "sucker's deal," Reuters reported.

France, the United States and Israel suspect Iran's nuclear facilities are being used to develop a nuclear bomb. Iran insists its nuclear program is for peaceful means. The Obama administration has said it was discussing an interim deal with Iran, "a first step," to relax some sanctions if Iran stops advancing its industrial-scale nuclear program.

According to Israeli newspaper Haaretz, Israeli officials said Iran would be asked under the deal to stop enriching uranium to 20% and to convert that stockpile into reactor fuel; not activate advanced centrifuges that are up to five times as fast as those currently operating, and reduce the number of centrifuges producing 3.5% enriched uranium. Iran was also asked not to activate its heavy water reactor, but could continue work to complete it, the paper said. Israel wants Iran to stop producing nuclear fuel and stop work at Arak.

The difficulty of the talks are a sign of how far both Iran's nuclear program and Western sanctions have progressed and how hard it is to roll them back, said Blaise Misztal, director of the Foreign Policy Project at the Bipartisan Policy Center, who has testified before Congress on Iran's nuclear program.

Iran has invested so much into increasing the pace, scale and efficiency of its nuclear fuel production program that it can't change course without losing face, Misztal said.

Western sanctions, spearheaded by legislation put in place by Congress, would be so hard to reinstate once repealed that lawmakers and others are pushing for real Iranian concessions to take place, not just an agreement, before offering such relief, Misztal said.

"It takes years to return sanctions," Misztal said. "And the (Obama) administration can't lift sanctions on its own. That requires an act of Congress and there's not much support for that at this point."

White House spokesman Jay Carney told reporters Friday that U.S. negotiators are working to secure a deal that "halts Iran's nuclear program from moving forward, and potentially rolls back parts of it."

The "first step" toward such an agreement, which Kerry was trying to secure in Geneva this weekend, would deal with Iran's most advanced nuclear activities and "increase transparencies so Iran will not be able to use the cover of talks to advance its program" while more comprehensive talks continue, Carney said.

An effective freeze would require stopping all of Iran's nuclear activities, Misztal said, including production of nuclear fuel that is 3.5% and that is 20% pure, installation of additional centrifuges to produce that fuel, research on advanced centrifuges that would enrich fuel faster and work on Iran's heavy water reactor at Arak.

And that "minimum freeze" would have to be accompanied by stricter inspections to make sure Iran abides by the agreement, Misztal said.

By all accounts that's not the kind of deal being discussed in Geneva, however, and the biggest reason is "how far (the Iranians) have come," Misztal said.

"The longer they keep their program going the more wedded they are to it. The harder it will be to give that up without losing face," he said.

The latest report by the United Nations nuclear watchdog, the International Atomic Energy Agency, found that Iran's nuclear program was advancing by almost every measure, according to a summary Misztal wrote in September.

Key findings of that report include:

â?¢ Production and stockpiles of low-enriched uranium are both at an all-time high.

â?¢ Production of medium-enriched uranium, which requires only 10% more work to reach weapons-grade, is at an all-time high. Iran has kept those stockpiles below the level Israel said would be its red line, however.

â?¢ And Iran has expanded its capacity to enrich more uranium faster, with thousands of centrifuges installed but not turned on, thousands more ready to be installed, and work continuing on more efficient models of centrifuges that allow Iran to produce nuclear fuel even faster.